项目 5 补齐：旧版线程 API（Suspend / Resume / Abort）与 ListBox

- 编译时把 Thread 的 Suspend / Resume / Abort、ThreadState、Sleep、new Thread 改写成平台的
  协作式实现：被挂起或终止的线程在 Sleep、后台改控件、调设备类库、弹提示框时停下或结束；
  ThreadStateException 等行为与 .NET Framework 一致；编辑器不再提示"已过时"
- ListBox：列表项、单选、SelectedIndexChanged 先于 Click、删除选中项后取消选中；
  ComboBox 与 ListBox 共用 ListControl 和列表项集合；设计器工具箱加"列表框"
- 评分规则的"包含"对列表框检查所有列表项
- 示例：项目 5 任务 2（烟雾，线程）、任务 3（推送灾情，二维数组、两个窗体、ListBox），
  参考答案修正书上直接 Abort 挂起线程、烟雾记成"发现火情"的问题
- 一直不换行的 Console 输出攒满 4096 字符先发出，避免占满内存
- 测试：旧版线程 API、ListBox 事件顺序、两个示例的端到端和评分测试

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

runtime/Sim.WinForms/Forms/ComboBox.cs

@@ -1,15 +1,11 @@
-using System.Collections;
-using System.Collections.Generic;
 using System.Drawing;
-using System.Linq;
 using System.Text.Json.Nodes;
 using Sim.Host;
 
 namespace System.Windows.Forms;
 
-public class ComboBox : Control
+public class ComboBox : ListControl
 {
-    private int _selectedIndex = -1;
     private ComboBoxStyle _dropDownStyle = ComboBoxStyle.DropDown;
 
     public ComboBox() => Items = new ObjectCollection(this);
@@ -31,15 +27,15 @@ public class ComboBox : Control
         set => SetProp(ref _dropDownStyle, value, nameof(DropDownStyle));
     }
 
-    public int SelectedIndex
+    public override int SelectedIndex
     {
-        get => _selectedIndex;
+        get => SelectedIndexValue;
         set
         {
             if (value < -1 || value >= Items.Count)
                 throw new ArgumentOutOfRangeException(nameof(value), $"“{value}”的值对于“SelectedIndex”无效。");
-            if (value == _selectedIndex) return;
-            SetProp(ref _selectedIndex, value, nameof(SelectedIndex));
+            if (value == SelectedIndexValue) return;
+            SetProp(ref SelectedIndexValue, value, nameof(SelectedIndex));
             // 选中项变化时 Text 随之变化（先 TextChanged，再 SelectedIndexChanged，与 WinForms 一致）
             Text = value >= 0 ? Items[value]?.ToString() ?? "" : "";
             OnSelectedIndexChanged(EventArgs.Empty);
@@ -49,19 +45,17 @@ public class ComboBox : Control
 
     public object? SelectedItem
     {
-        get => _selectedIndex >= 0 ? Items[_selectedIndex] : null;
+        get => SelectedIndexValue >= 0 ? Items[SelectedIndexValue] : null;
         set => SelectedIndex = value == null ? -1 : Items.IndexOf(value);
     }
 
     public string SelectedText { get; set; } = "";
 
     public event EventHandler? SelectedIndexChanged;
-    public event EventHandler? SelectedValueChanged;
     public event EventHandler? DropDown;
     public event EventHandler? DropDownClosed;
 
     protected virtual void OnSelectedIndexChanged(EventArgs e) => SelectedIndexChanged?.Invoke(this, e);
-    protected virtual void OnSelectedValueChanged(EventArgs e) => SelectedValueChanged?.Invoke(this, e);
     protected virtual void OnDropDown(EventArgs e) => DropDown?.Invoke(this, e);
     protected virtual void OnDropDownClosed(EventArgs e) => DropDownClosed?.Invoke(this, e);
 
@@ -84,7 +78,7 @@ public class ComboBox : Control
             case "text" when _dropDownStyle != ComboBoxStyle.DropDownList:
                 SetTextFromUser(action.Value ?? "");
                 var match = Items.IndexOf(Text);
-                if (match != _selectedIndex) _selectedIndex = match;
+                if (match != SelectedIndexValue) SelectedIndexValue = match;
                 break;
             default:
                 base.OnUserAction(action);
@@ -92,85 +86,28 @@ public class ComboBox : Control
         }
     }
 
-    internal void ItemsChanged()
+    internal override void ItemsChanged()
     {
-        if (_selectedIndex >= Items.Count) _selectedIndex = -1;
-        NotifyChanged(nameof(Items), Items.Select(i => i?.ToString() ?? "").ToArray());
+        NotifyChanged(nameof(Items), ItemTexts(Items));
+        NotifyChanged(nameof(SelectedIndex), SelectedIndexValue);
+    }
+
+    internal override void ItemsCleared()
+    {
+        SelectedIndex = -1;
+        ItemsChanged();
     }
 
     protected override void WriteProps(JsonObject props)
     {
         base.WriteProps(props);
-        props["Items"] = PropValue.From(Items.Select(i => i?.ToString() ?? "").ToArray());
-        props["SelectedIndex"] = _selectedIndex;
+        props["Items"] = PropValue.From(ItemTexts(Items));
+        props["SelectedIndex"] = SelectedIndexValue;
         props["DropDownStyle"] = _dropDownStyle.ToString();
     }
 
-    public class ObjectCollection : IList, IEnumerable<object?>
+    public class ObjectCollection : ListItemCollection
     {
-        private readonly List<object?> _items = new();
-        private readonly ComboBox _owner;
-
-        public ObjectCollection(ComboBox owner) => _owner = owner;
-
-        public int Count => _items.Count;
-        public bool IsReadOnly => false;
-        bool IList.IsFixedSize => false;
-        bool ICollection.IsSynchronized => false;
-        object ICollection.SyncRoot => this;
-
-        public object? this[int index]
-        {
-            get => _items[index];
-            set
-            {
-                _items[index] = value;
-                _owner.ItemsChanged();
-            }
-        }
-
-        public int Add(object? item)
-        {
-            if (item == null) throw new ArgumentNullException(nameof(item), "值不能为 null。");
-            _items.Add(item);
-            _owner.ItemsChanged();
-            return _items.Count - 1;
-        }
-
-        public void AddRange(object[] items)
-        {
-            _items.AddRange(items);
-            _owner.ItemsChanged();
-        }
-
-        public void Insert(int index, object? item)
-        {
-            _items.Insert(index, item);
-            _owner.ItemsChanged();
-        }
-
-        public void Remove(object? item)
-        {
-            if (_items.Remove(item)) _owner.ItemsChanged();
-        }
-
-        public void RemoveAt(int index)
-        {
-            _items.RemoveAt(index);
-            _owner.ItemsChanged();
-        }
-
-        public void Clear()
-        {
-            _items.Clear();
-            _owner.SelectedIndex = -1;
-            _owner.ItemsChanged();
-        }
-
-        public bool Contains(object? item) => _items.Contains(item);
-        public int IndexOf(object? item) => _items.IndexOf(item);
-        public void CopyTo(Array array, int index) => ((ICollection)_items).CopyTo(array, index);
-        public IEnumerator<object?> GetEnumerator() => _items.GetEnumerator();
-        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+        public ObjectCollection(ComboBox owner) : base(owner) { }
     }
 }

runtime/Sim.WinForms/Forms/Control.cs

@@ -104,6 +104,7 @@ public class Control : Component, IWin32Window
         get => _text;
         set
         {
+            LegacyThreads.CheckPoint();
             value ??= "";
             if (_text == value) return;
             EnsureThreadAccess();
@@ -279,6 +280,9 @@ public class Control : Component, IWin32Window
                 OnClick(args);
                 OnMouseClick(args);
                 break;
+            case "doubleClick":
+                OnDoubleClick(EventArgs.Empty);
+                break;
             case "mouseDown":
                 OnMouseDown(new MouseEventArgs(ToMouseButtons(action.Button), 1, action.X, action.Y, 0));
                 break;
@@ -354,6 +358,8 @@ public class Control : Component, IWin32Window
     /// <summary>修改字段并在需要时通知浏览器；返回值表示是否真的改变</summary>
     protected bool SetProp<T>(ref T field, T value, string prop)
     {
+        // 后台线程改界面时响应 Suspend / Abort（教材的线程方法每次循环都会改控件）
+        LegacyThreads.CheckPoint();
         if (EqualityComparer<T>.Default.Equals(field, value)) return false;
         EnsureThreadAccess();
         field = value;

runtime/Sim.WinForms/Forms/ListBox.cs

@@ -0,0 +1,144 @@
+using System.Drawing;
+using System.Text.Json.Nodes;
+using Sim.Host;
+
+namespace System.Windows.Forms;
+
+public enum SelectionMode { None, One, MultiSimple, MultiExtended }
+
+/// <summary>列表框（教材项目 5 任务 3 显示历史灾情记录）。只支持单选。</summary>
+public class ListBox : ListControl
+{
+    private int _itemHeight = 12;
+    private BorderStyle _borderStyle = BorderStyle.Fixed3D;
+
+    public ListBox() => Items = new ObjectCollection(this);
+
+    protected override Size DefaultSize => new(120, 96);
+
+    public ObjectCollection Items { get; }
+
+    public bool FormattingEnabled { get; set; }
+    public bool IntegralHeight { get; set; } = true;
+    public bool HorizontalScrollbar { get; set; }
+    public bool ScrollAlwaysVisible { get; set; }
+    public bool MultiColumn { get; set; }
+    public bool Sorted { get; set; }
+    public SelectionMode SelectionMode { get; set; } = SelectionMode.One;
+    public int TopIndex { get; set; }
+
+    public int ItemHeight
+    {
+        get => _itemHeight;
+        set => SetProp(ref _itemHeight, value, nameof(ItemHeight));
+    }
+
+    public BorderStyle BorderStyle
+    {
+        get => _borderStyle;
+        set => SetProp(ref _borderStyle, value, nameof(BorderStyle));
+    }
+
+    public override int SelectedIndex
+    {
+        get => SelectedIndexValue;
+        set
+        {
+            if (value < -1 || value >= Items.Count)
+                throw new ArgumentOutOfRangeException(nameof(value), $"“{value}”的值对于“SelectedIndex”无效。");
+            if (!SetProp(ref SelectedIndexValue, value, nameof(SelectedIndex))) return;
+            OnSelectedIndexChanged(EventArgs.Empty);
+            OnSelectedValueChanged(EventArgs.Empty);
+        }
+    }
+
+    public object? SelectedItem
+    {
+        get => SelectedIndexValue >= 0 ? Items[SelectedIndexValue] : null;
+        set => SelectedIndex = value == null ? -1 : Items.IndexOf(value);
+    }
+
+    /// <summary>和 WinForms 一样，列表框的 Text 是选中项的文字；赋值时选中文字相同的项</summary>
+    public override string Text
+    {
+        get => GetItemText(SelectedItem);
+        set
+        {
+            var index = FindStringExact(value ?? "");
+            if (index >= 0) SelectedIndex = index;
+        }
+    }
+
+    public event EventHandler? SelectedIndexChanged;
+
+    protected virtual void OnSelectedIndexChanged(EventArgs e) => SelectedIndexChanged?.Invoke(this, e);
+
+    public void ClearSelected() => SelectedIndex = -1;
+
+    public void SetSelected(int index, bool value)
+    {
+        if (value) SelectedIndex = index;
+        else if (index == SelectedIndexValue) SelectedIndex = -1;
+    }
+
+    public bool GetSelected(int index) => index == SelectedIndexValue;
+
+    /// <summary>第一个以 s 开头的项（不区分大小写），没有时返回 -1</summary>
+    public int FindString(string s)
+    {
+        for (var i = 0; i < Items.Count; i++)
+            if (GetItemText(Items[i]).StartsWith(s, StringComparison.OrdinalIgnoreCase)) return i;
+        return -1;
+    }
+
+    public int FindStringExact(string s)
+    {
+        for (var i = 0; i < Items.Count; i++)
+            if (string.Equals(GetItemText(Items[i]), s, StringComparison.OrdinalIgnoreCase)) return i;
+        return -1;
+    }
+
+    public void BeginUpdate() { }
+    public void EndUpdate() { }
+
+    protected override void OnUserAction(UserAction action)
+    {
+        switch (action.Action)
+        {
+            case "select":
+                // 和 WinForms 一样，按下鼠标时先改变选中项，松开后才触发 Click
+                if (action.Index >= 0 && action.Index < Items.Count) SelectedIndex = action.Index;
+                base.OnUserAction(new UserAction { Action = "click", X = action.X, Y = action.Y });
+                break;
+            default:
+                base.OnUserAction(action);
+                break;
+        }
+    }
+
+    internal override void ItemsChanged()
+    {
+        NotifyChanged(nameof(Items), ItemTexts(Items));
+        NotifyChanged(nameof(SelectedIndex), SelectedIndexValue);
+    }
+
+    internal override void ItemsCleared()
+    {
+        SelectedIndex = -1;
+        ItemsChanged();
+    }
+
+    protected override void WriteProps(JsonObject props)
+    {
+        base.WriteProps(props);
+        props["Items"] = PropValue.From(ItemTexts(Items));
+        props["SelectedIndex"] = SelectedIndexValue;
+        props["ItemHeight"] = _itemHeight;
+        props["BorderStyle"] = _borderStyle.ToString();
+    }
+
+    public class ObjectCollection : ListItemCollection
+    {
+        public ObjectCollection(ListBox owner) : base(owner) { }
+    }
+}

runtime/Sim.WinForms/Forms/ListControl.cs

@@ -0,0 +1,114 @@
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace System.Windows.Forms;
+
+/// <summary>ComboBox 和 ListBox 的共同基类：列表项、选中项</summary>
+public abstract class ListControl : Control
+{
+    /// <summary>选中项的序号。列表项增删时直接调整（和 WinForms 一样不触发 SelectedIndexChanged）</summary>
+    private protected int SelectedIndexValue = -1;
+
+    public abstract int SelectedIndex { get; set; }
+
+    public string DisplayMember { get; set; } = "";
+    public string ValueMember { get; set; } = "";
+
+    public event EventHandler? SelectedValueChanged;
+
+    protected virtual void OnSelectedValueChanged(EventArgs e) => SelectedValueChanged?.Invoke(this, e);
+
+    public string GetItemText(object? item) => item?.ToString() ?? "";
+
+    /// <summary>列表项变化后调用：把新的列表和选中项发给浏览器</summary>
+    internal abstract void ItemsChanged();
+
+    /// <summary>Items.Clear() 时调用：先取消选中，再刷新列表</summary>
+    internal abstract void ItemsCleared();
+
+    internal void ItemInserted(int index)
+    {
+        if (SelectedIndexValue >= index) SelectedIndexValue++;
+        ItemsChanged();
+    }
+
+    /// <summary>删掉的正是选中项时取消选中，删掉前面的项时选中项序号前移</summary>
+    internal void ItemRemoved(int index)
+    {
+        if (SelectedIndexValue == index) SelectedIndexValue = -1;
+        else if (SelectedIndexValue > index) SelectedIndexValue--;
+        ItemsChanged();
+    }
+
+    protected string[] ItemTexts(IEnumerable<object?> items) => items.Select(GetItemText).ToArray();
+}
+
+/// <summary>ComboBox.ObjectCollection 和 ListBox.ObjectCollection 共用的实现</summary>
+public abstract class ListItemCollection : IList, IEnumerable<object?>
+{
+    private readonly List<object?> _items = new();
+    private readonly ListControl _owner;
+
+    private protected ListItemCollection(ListControl owner) => _owner = owner;
+
+    public int Count => _items.Count;
+    public bool IsReadOnly => false;
+    bool IList.IsFixedSize => false;
+    bool ICollection.IsSynchronized => false;
+    object ICollection.SyncRoot => this;
+
+    public object? this[int index]
+    {
+        get => _items[index];
+        set
+        {
+            _items[index] = value;
+            _owner.ItemsChanged();
+        }
+    }
+
+    public int Add(object? item)
+    {
+        if (item == null) throw new ArgumentNullException(nameof(item), "值不能为 null。");
+        _items.Add(item);
+        _owner.ItemsChanged();
+        return _items.Count - 1;
+    }
+
+    public void AddRange(object[] items)
+    {
+        _items.AddRange(items);
+        _owner.ItemsChanged();
+    }
+
+    public void Insert(int index, object? item)
+    {
+        _items.Insert(index, item);
+        _owner.ItemInserted(index);
+    }
+
+    public void Remove(object? item)
+    {
+        var index = _items.IndexOf(item);
+        if (index >= 0) RemoveAt(index);
+    }
+
+    public void RemoveAt(int index)
+    {
+        _items.RemoveAt(index);
+        _owner.ItemRemoved(index);
+    }
+
+    public void Clear()
+    {
+        _items.Clear();
+        _owner.ItemsCleared();
+    }
+
+    public bool Contains(object? item) => _items.Contains(item);
+    public int IndexOf(object? item) => _items.IndexOf(item);
+    public void CopyTo(Array array, int index) => ((ICollection)_items).CopyTo(array, index);
+    public IEnumerator<object?> GetEnumerator() => _items.GetEnumerator();
+    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+}

runtime/Sim.WinForms/Host/LegacyThreads.cs

@@ -0,0 +1,165 @@
+using System;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+using System.Threading;
+
+namespace Sim.Host;
+
+/// <summary>
+/// 教材项目 5 用到的旧版线程 API：Thread.Suspend / Resume / Abort 在新版 .NET 上会抛出 PlatformNotSupportedException。
+/// 编译时把学生代码里对它们（以及 new Thread、Thread.Sleep、ThreadState）的调用改写成这里的方法（见 Sim.Runner/LegacyThreadRewriter.cs）。
+/// <para>
+/// 新版 .NET 不能从外部强行停住或中止一个线程，所以这里是"协作式"的：被挂起或中止的线程在下一个检查点停下或结束。
+/// 检查点是 Thread.Sleep、从后台线程修改控件属性、调用设备类库、弹出提示框，
+/// 教材里的线程方法每次循环都会经过它们，看到的效果和 .NET Framework 一致。
+/// </para>
+/// </summary>
+[EditorBrowsable(EditorBrowsableState.Never)]
+public static class LegacyThreads
+{
+    private sealed class State
+    {
+        public volatile bool Suspended;
+        public volatile bool AbortRequested;
+    }
+
+    // 线程少、操作不频繁，用一把锁保护所有线程的状态；挂起和休眠都在这把锁上等待
+    private static readonly object Gate = new();
+    private static readonly ConditionalWeakTable<Thread, State> States = new();
+
+    /// <summary>当前线程是学生用 new Thread 创建的线程时，指向它的状态</summary>
+    [ThreadStatic] private static State? _current;
+
+    private static State StateOf(Thread thread) => States.GetValue(thread, static _ => new State());
+
+    // ---------- 改写后的调用 ----------
+
+    /// <summary>new Thread(GetData) → new Thread(Wrap(new ThreadStart(GetData)))：线程被中止时安静地结束</summary>
+    public static ThreadStart Wrap(ThreadStart start) => () => RunThread(() => start());
+
+    public static ParameterizedThreadStart Wrap(ParameterizedThreadStart start) => obj => RunThread(() => start(obj));
+
+    private static void RunThread(Action body)
+    {
+        var state = StateOf(Thread.CurrentThread);
+        _current = state;
+        try
+        {
+            // 启动前就被 Abort 的线程（.NET Framework 里启动后立即结束）
+            CheckPoint(state);
+            body();
+        }
+        catch (ThreadAbortedException)
+        {
+            // 和 .NET Framework 一样，被中止的线程结束时不算未处理的异常
+        }
+    }
+
+    public static void Suspend(Thread thread)
+    {
+        lock (Gate)
+        {
+            if ((thread.ThreadState & (ThreadState.Unstarted | ThreadState.Stopped)) != 0)
+                throw new ThreadStateException("线程没有在运行，无法挂起。");
+            StateOf(thread).Suspended = true;
+        }
+        // 线程挂起自己：立即停下，直到别的线程调用 Resume
+        if (thread == Thread.CurrentThread) CheckPoint(StateOf(thread));
+    }
+
+    public static void Resume(Thread thread)
+    {
+        lock (Gate)
+        {
+            var state = StateOf(thread);
+            if (!state.Suspended) throw new ThreadStateException("线程没有被挂起，无法继续（Resume 只能用在调用过 Suspend 的线程上）。");
+            state.Suspended = false;
+            Monitor.PulseAll(Gate);
+        }
+    }
+
+    public static void Abort(Thread thread) => Abort(thread, null);
+
+    public static void Abort(Thread thread, object? stateInfo)
+    {
+        lock (Gate)
+        {
+            if ((thread.ThreadState & ThreadState.Stopped) != 0) return;
+            var state = StateOf(thread);
+            state.AbortRequested = true;
+            // 正在 Thread.Sleep 的线程立即醒来结束
+            Monitor.PulseAll(Gate);
+            // .NET Framework 不能直接中止挂起的线程：抛出异常，等它被 Resume 后才结束
+            if (state.Suspended) throw new ThreadStateException("线程已挂起，不能直接终止。先调用 Resume() 让线程继续，再调用 Abort()。");
+        }
+        if (thread == Thread.CurrentThread) throw new ThreadAbortedException();
+    }
+
+    /// <summary>thd.ThreadState：在真实状态上加上挂起、请求中止</summary>
+    public static ThreadState GetThreadState(Thread thread)
+    {
+        var actual = thread.ThreadState;
+        if (!States.TryGetValue(thread, out var state) || (actual & ThreadState.Stopped) != 0) return actual;
+        var result = actual & (ThreadState.Background | ThreadState.Unstarted);
+        if (state.Suspended) result |= ThreadState.Suspended;
+        else if ((actual & ThreadState.Unstarted) == 0) result |= actual & ThreadState.WaitSleepJoin;
+        if (state.AbortRequested) result |= ThreadState.AbortRequested;
+        return result;
+    }
+
+    public static void Sleep(int millisecondsTimeout)
+    {
+        var state = _current;
+        if (state == null)
+        {
+            Thread.Sleep(millisecondsTimeout);
+            return;
+        }
+        if (millisecondsTimeout < Timeout.Infinite) throw new ArgumentOutOfRangeException(nameof(millisecondsTimeout), "休眠时间不能是负数（-1 表示一直休眠）。");
+        CheckPoint(state);
+        var deadline = Environment.TickCount64 + millisecondsTimeout;
+        lock (Gate)
+        {
+            // 休眠中被 Abort 时提前醒来；被 Suspend 的线程睡完后在检查点停下
+            while (!state.AbortRequested)
+            {
+                if (millisecondsTimeout == Timeout.Infinite)
+                {
+                    Monitor.Wait(Gate);
+                    continue;
+                }
+                var remaining = deadline - Environment.TickCount64;
+                if (remaining <= 0) break;
+                Monitor.Wait(Gate, (int)remaining);
+            }
+        }
+        CheckPoint(state);
+    }
+
+    public static void Sleep(TimeSpan timeout) => Sleep((int)timeout.TotalMilliseconds);
+
+    // ---------- 检查点 ----------
+
+    /// <summary>平台内部使用：学生创建的线程在这里响应 Suspend 和 Abort（其他线程直接返回）</summary>
+    public static void CheckPoint()
+    {
+        var state = _current;
+        if (state != null) CheckPoint(state);
+    }
+
+    private static void CheckPoint(State state)
+    {
+        if (!state.Suspended && !state.AbortRequested) return;
+        lock (Gate)
+        {
+            while (state.Suspended) Monitor.Wait(Gate);
+            if (state.AbortRequested) throw new ThreadAbortedException();
+        }
+    }
+}
+
+/// <summary>线程被 Abort 时在线程里抛出（对应 .NET Framework 的 ThreadAbortException）</summary>
+public sealed class ThreadAbortedException : Exception
+{
+    public ThreadAbortedException() : base("正在中止线程。") { }
+}

runtime/Sim.WinForms/Host/SimHost.cs

@@ -77,13 +77,17 @@ public static class SimHost
 
     public static void SendConsole(string text) => Send(new JsonObject { ["type"] = "console", ["text"] = text });
 
-    public static void SendDevice(string device, string action, object? data) => Send(new JsonObject
+    public static void SendDevice(string device, string action, object? data)
     {
-        ["type"] = "device",
-        ["device"] = device,
-        ["action"] = action,
-        ["data"] = PropValue.From(data),
-    });
+        LegacyThreads.CheckPoint();
+        Send(new JsonObject
+        {
+            ["type"] = "device",
+            ["device"] = device,
+            ["action"] = action,
+            ["data"] = PropValue.From(data),
+        });
+    }
 
     // ---------- 异常 ----------
 
@@ -121,6 +125,7 @@ public static class SimHost
     /// </summary>
     public static JsonNode? Request(JsonObject message)
     {
+        LegacyThreads.CheckPoint();
         var id = Interlocked.Increment(ref _nextRequestId);
         var pending = new PendingRequest();
         Requests[id] = pending;